Figure 1: Clinical and histological picture of the case. (a) Solitary, 4-mm sized firm reddish nodule with a central keratotic plug on the occipital scalp. (b) Cup-shaped keratin-filled invagination with hyperkeratosis, acanthosis, and a marked suprabasal acantholytic cleft in the epidermis (hematoxylin and eosin [H and E], magnification ×40). (c) Numerous projecting villi lining a single layer of basal cells and acantholytic and dyskeratotic cells (H and E, magnification × 200)